Defending London Marathon champion Wilson Kipsang believes the presence of Mo Farah in the field can help someone set a new world record this Sunday, as doubts emerge about the Brit's new sprint coach.

Farah, the double Olympic champion, is set to run half of the marathon on April 21, and Kipsang believes his presence - as both a frontrunner and an attraction for the crowds - can help those set to go the full distance do so in record time.

"He can help us break the world record," Kipsang said. "I think it's going to happen. I think he will help control the pace.

"He's a big name and the crowd will be cheering so it gives us an extra boost. It's good for him but it's good for us too."

Farah may face some difficult questions on Sunday, however, after beginning to work with controversial sprinting coach John Smith.

Farah's head coach, Alberto Salazar, believes the Brit needs to improve his sprint finish if he is to keep developing as a runner - and so sent Farah to see Smith, who previously coached Maurice Greene to 100m Olympic gold in 2000.

However, Smith was also named in official documents involved with the BALCO scandal, after meeting with the infamous Victor Conte. The American has always denied any wrongdoing.

In the meantime, the London Marathon threatens to be overshadowed by the tragic events of Boston, but Kipsang insisted he had no doubts about competing.

"We shall have no fear because security matters will be put in place," he said.

Event chief executive Nick Bitel added: "It's not about budgets or money, it's about putting up the right numbers to send out the right message.

"London is one of the safest cities in the world and we saw last year, with the incredible security effort around the Olympics, that there is no finer force at answering these types of threat."

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